code: def run_dist(rank, world_size, port):
      config = {}
      colossalai.launch(
          config=config,
          rank=rank,
          world_size=world_size,
          host="localhost",
          port=port,
          backend="nccl",
      )
      exam_fwd_bwd()
  
file_path: colossalai/tests/test_auto_parallel/test_offload/test_perf.py
imports: import time
  import pytest
  import torch
  from torch.utils._pytree import tree_map
  import colossalai
  from colossalai.auto_parallel.offload.amp_optimizer import AMPOptimizer
  from colossalai.auto_parallel.offload.mem_optimize import memory_optimize
  from colossalai.auto_parallel.offload.solver import NOT_NVML
  from colossalai.fx.profiler import parameter_size
  from colossalai.nn.optimizer import HybridAdam
  from colossalai.testing import parameterize, rerun_if_address_is_in_use, spawn
  from colossalai.utils import get_current_device
  from colossalai.zero import ColoInitContext, zero_model_wrapper, zero_optim_wrapper
  from tests.test_auto_parallel.test_offload.model_utils import *
  from tests.test_tensor.common_utils import set_seed
label_desc: Use image node_id 2 for calling a global function with example usage: run_dist(rank, world_size, port) without return types